package com.codewsq.exer.syn3;

/*
 * 线程安全的懒汉式单例模式
 * */
public class Singleton {

    private static volatile Singleton instance = null;

    private Singleton() {
    }

    public static Singleton getInstance() {
        if (instance == null) {
            synchronized (Singleton.class) {
                if (instance == null) {
                    instance = new Singleton();
                }
            }
        }
        return instance;
    }

}
